Centrifugal pumps, in particular for feeding fuel to fuel injection engines



March 1959 HQPH. G. A. R. VON ZBOROWSKI 2,

CENTRIFUGAL PUMPS. IN PARTICULAR FOR FEEDING FUEL TO FUELINJECTIONENGINES Filed Dec. 1, 1952 4 Sheets-Sheeti f. //0 Zaranm er 4M 1 4TI'OR/VE Y:

March 3, 1959' H. PH. G. A. R. vo CENTRI AL PUMPS, IN P N ZBOROWSKI 2,m; ARTICULAR FOR FEEDING FUEL TO FUEL INJECTION ENGINES 4 Sheets-Sheet 2Filed Dec. 1. 1952 March 3, 1959 H,

' CENTRIF PH. G. A. R. VON ZEOROWSK! 2,875,696 UGAL Pu! IN PARTICULARFOR FEEDING FUEL TO L INJECTION ENGINES 4 Sheets-Sheet 3 Filed Dec. 1,1952 Q) Q Ij Q Q m s I N March 1 H. PH. G. A. R. VON ZBO'ROWSKI 2,

CENTRIFUGAL PUMPS, IN PARTICULAR FOR FEEDING FUEL o FUEL INJECTIONENGINES Filed Dec. 1, 1952 4 SheetS -S'net 4 United States Patent2,875,696 ICENTRIFUGAL PUMPS, IN PARTICULAR FOR FEEDING FUEL T0 FUELINJECTION ENGINES "Helmnt Pl'I. G. A. R. von Zborbwski, Brunoy, FranceApplication December 1, 1952, Serial No. 323,493 Claims priority,application France December 5, 1951 13 Claims. (Cl. lll3=103) Thepresent invention relates to centrifugal pumps, and it is moreespecially concerned with centrifugal pumps. The chief object of thepresent invention is to provide a centrifugal pump which is free fromany leakage of liquid past the ball hearings in which the pump rotorshaft is mounted, and this without involving too much friction whichwould result in a quick wear and tear of the parts offthis pu Preferredembodiments of my invention will be hereinafter described with reference"to the accompanying drawings', given merely by way of example, and inwhich:

Fig. 1 of these drawings shows in axial section a fuel for fuelinjection engines made according to a first embodiment of my invention;j

Fig. 2 is a partial front view of an element of the pump of Fig. 1;

\ Figs} and 4 are circular sections respectively on the lines III-IIIand IV-IV of Fig. 2; h

Fig. 5 shows, in axial half-section, a modification of ther'otor of thepump illustrated by Fig. 1;

Figs. 6 and 7 illustrate two devices according to my invention fordistributing the discharge diffusers at the periphery of the rotor;

Figs. 8 and 9 show, respectively in longitudinal section and in crosssection on the line IXIX of Fig. 8, a particulai" embodiment of such adiffuser;

Fig'. 10 illustrates a modification of the flow rate adjustifig meansincluded in the diffuser of Fig. 8;

Fig. 11 shows the characteristic curves of the pump according to myinvention and of a conventional pump;

Fig. 12 shows, in axial half-section, a fuel pump made according to asecond embodiment of my invention;

Fig. 13 shows, in horizontal section, a modification of a deliverydiffuser for such a pump.

I will now describe, by way of example, a centrifugal pump for feedingfuel to an engine such as a turbo-jet or a turbo-prop.

I This pump includes a casing 1 one of the sides of which forms atubular extension 2 supporting, through ball bearings 3, the drivingshaft 4 of the centrifugal rotor, the other side of said casing beingconnected in a fluidtight mariner with a conduit 5 for the feed of fuel.

A rotor 6 provided with radial blades 7 is fitted in a housing C ofcentrifugal shape proyided inside casing 1. Thisrotor will first besupported to be rigid with the drivir'ig shaft 4. p

Upstreamof this rotor, toward conduit 5, there is provided a set of'fixd guiding blades 8.

I provide, in the periphery of casing 1, one or several deliverydiffusers, the minimum section (inlet section) of such a diffuser beingvisible at S on Fig. l.

It will be readily understood that it is necessary, in order toavoidlleaks through ball bearings 3, to provide,- in addition to thepacking joint 9 which is usually pro vided in such bearings; a specialdevice capable of acting in opposition to the delivery pressure of thepump.

For this purpose and according to my invention,

I provide, on the inside of casing 1 and moving the same rotary speed asdriving shaft 4, an axially slidable element constituted, according to afirst embodiment of my invention, by a disc or wheel 10 distinct fromcentrifugal rotor 6 and slidable thereon owing to the provision ofsplines 10a;

I provide a return elastic system which tends constant- 1y to apply theouter face of wheel 10 against a fixed annular packing joint 11 carriedby a wall of casing 2 1acated opposite said wheel;

I provide another packing joint in order to prevent leaks along the hubof wheel 10, or, to be more accurate, along splines 10a, this secondpacking joint being advan- :tagcously constituted by an elasticdiaphragm 12 inser ted between rotor 6 and wheel 10, whereby saidpacking diaphragin plays at the same time the part of elastic returnsystem for said wheel 10;

I provide, on the outer face of wheel 10, a set of inclined surfaces 13(see Figs. 1, 2 and 3), preferably located at the periphery of saidWheel, the direction of these inclined surfaces 13 being such thathydrodynamicefforts are created during the rotation of the rotor whichtend to push wheel 10 axially against the action of the elastic returnsystem 12, thus causing the outer face of wheel 10 to move away from theannular packing joint 11; j

At least the outer face of wheellll carries a plurality of centrifugalblades 14 (visible on Figs, 1, 2 and 4) vconstituting a kind ofauxiliary pump caapble of driving back the liquid which would have atendency to infiltrate between the outer face of wheel 10 and casing 1in the direc tion of the annular packing joint 11, the latter being ofcourse nearer to the axis of the rotor than blades 14 and inclinedsurfaces 13. p j

' Preferably (in order to avoid beat phenomena during the axial slidingmovement of wheel 10), when wheel 10 is in contact with annular joint11, the periphery of said Wheel is as close as possible to thecorresponding face of casing 1, for which purpose, advantageously, theedge of wheel. Ill is curved toward bearing 2.

It is necessary, in order to enable the hydraulic ma chine constitutedby wheel 10 to start working, to provide orifices 15 for the passage ofliquid from the inner face to the outer face of said Wheel 10,

It should be noted that it will be advantageous to pro vide casing 1,opposite the face of rotor 6 which is not fitted with blades, with ashoulder 1a which limits an auxiliary chamber D forming a housing forwheel 10, the pressure in this chamber D being substantially lower thanthe delivery pressure due to the fact that the liquid located betweenthe corresponding faces ofrotor 6 and shoulder 1a is driven in rotationonly by friction, whereas the liquid located along the face of the rotorprovided with blades is driven at a much higher speed by said blades.

This system works as follows:

At rest, elastic diaphragm 12 applies wheel 10 against annular joint 11and there remains only a very small pas sage between the periphery ofsaid wheel Ill and the cor responding wall of casing 1, fluidtig htnessbeing ensured exclusively by said annular joint 11. As soon as rotor 6is driven by shaft 4, blades 7 produce, at the outlets of the deliverydiffusers, a pressure which is partly transmitted into housing D insidewhich wheel 10 participates in the rotary movement of rotor 6.

When Wheel 10 is driven in rotation, the liquid located between thiswheel and the corresponding face of casing 1 reacts upon inclinedsurfaces 13 and pushes wheel 10 back against the action of elasticreturn system 12. The outer face of Wheel 10 then ceases to be incontact with the annular packing joint 11 and I thus avoid the quickwearing of said joint which would certainly take place 3 if a frictionalcontact were constantly maintained between fixed joint 11 and wheelrunning at a high speed. Radial blades 14 then drive back, toward theperiphery of wheel 10 and housing D, the infiltrations of liquid whichwould otherwise take place in the direction of annular joint 11.

As the counter-pressure created by centrifugal blades 14 and by the faceof the rotor located opposite shoulder 1a varies proportionally to thepressure created by centrifugal blades 7, the effect achieved by thesystem will be independent of the speed of rotation of the pump and willremain satisfactory even during acceleration or slowing down periods.

I thus obtain a single stage pump which is perfectly fluidtight andtherefore capable of operating at high speed so as to permit ofobtaining high delivery pressures.

Furthermore, this pump is of a very simple construction and may be mademostly of pieces of a light metal machined with a relatively lowprecision, in view of the fact that no part of the device for preventingleaks is subjected to a frictional action once the pump has been set inrotation.

According to another feature of my invention, the blades 7 of rotor 6(which blades may be made straight in view of the fact that the radialspeed of the liquid is practically negligible as compared to itstangential speed in the vicinity of the trailing edge of the blades) arearranged in such manner that their trailing edge is thinned out, saidedge being preferably limited, as shown ;by Fig. 6, by a flat wall 7atoward the front and by a convex wall 7b toward the rear (direction ofrotation of the blades shown by arrow F) Furthermore, I provide, in thetrailing edge thus constituted, a notch 6 (see Figs. 5 and 6) the shapeof which corresponds to that of the diffuser inlet.

In order to have the curved edge of this notch as sharp as the remainderof the trailing edge of the blade, I provide in convex wall 7b oppositenotch e a recess s.

Thus I avoid pressure shocks when one of the blades passes opposite theinlet of the diffuser.

*It should also be noted that the reduction of pressure resulting fromthe flow of a small amount of liquid between blade 7 and easing 1 may bereduced by surrounding blades 7 on their whole length by an annularcasing 16, as shown by Fig. 5.

According to another feature of my invention, which relates to theposition of the outlet diffusers, I provide at least two diffusers 17which are so positioned that when the inlet section of one of them islocated opposite one blade 7, the inlet section of the other diffuser islocated between two blades.

Such an arrangement has been shown in Fig. 6 in the case of a rotorincluding three blades and in Fig. 7 in the case of a rotor includingonly two blades.

In both cases, it has been supposed by way of exampic that there areonly two diffusers 17 and that, when the inlet section of one of them islocated opposite one blade, the inlet section of the other is located atmiddistance between the two adjacent blades.

It should be noted that it is of interest to locate the inlet section Sof every diffuser as close as possible to the part of the trailing edgeof the blades, said section S being even advantageously located, when ablade passes therealong, in the notch e provided in said trailing edge(see Fig. 5)

Concerning the diffusers 17 proper, they are preferably provided withmeans for adjusting their minimum section S.

' Such means make it possible to adjust the delivery flow rate of thepump while keeping the pressure substantially constant.

If, as it will first be supposed, diffuser 17 is of rectangular crosssection, the adjusting means may be constit uted, as shown by Figs. 8 to10, by a shutter 18 pivoted about an axis 19 located in such manner thatthe pivoting '4 movement of the shutter about said axis causes avariation of the inlet section S of the diffuser, said section beingpreferably fully cleared when shutter 18 is in position of rest.

When the engine driven by the pump is intended to work at constant speed(which speed must however be adjustable), it may be sutficient toprovide, for controlling the shutters 18 of every diffuser, mere screws20 advantageously connected to the shutters by links 21 swivelled at 22,said screws being protected and locked by nutlocks 23.

If the engine driven by the pump must, on the contrary, undergovariations of speed in the course of this operation, which is the casein particular of an aircraft engine, it will be advantageous to have allthe shutters 18 of the respective diffusers actuated simultaneously,each for instance, as shown by Fig. 10, through a disc 24 carrying aneccentric pin engaged in a slot of shutter 18, this system then actingas a fuel distribution adjusting system, that is to say as theequivalent of a throttle pedal.

An important functional advantage inherent in pumps made as abovedescribed lies in the shape of the characteristic curve of the pump.

In Fig. 11, there are plotted in ordinates the delivery pressures and inabscissas the delivery flow rates this diagram showing in solid linesthe curve of a pump made according to my invention (corresponding to agiven speed of operation), whereas the characteristic curve of aconventional pump working at the same speed is shown in dotted lines.

It appears clearly that with a pump according to my invention, there isa very wide margin of adjustment of the flow rate, inside which thedelivery pressure remains substantially constant, which is not the casewith a conventional pump where the margin in question is restricted tothe vicinity of flow rate value D corresponding to the top point of theconventional characteristic curve of parabolic shape.

In what precedes, it has been supposed that the disc 10 of the packingsystem is distinct from the centrifugal rotor 6 of the pump.

But I may also, according to another embodiment illustrated by Fig. 12,make in a single piece the centrifugal rotor 6 and the disc. In Fig. 12,said disc is designated by reference numeral 10b.

Inclined surfaces 13 and radial blades 14 similar to those of Fig. l arecarried by said disc 10b, which is in tegral with blades 7.

The liquidtight diaphragm 12 of the construction of Fig. 1 is no longernecessary. But the resilient action of this diaphragm is exerted, in theconstruction of Fig. 12, by a mere elastic ring 12a inserted betweencasing 1 and the outer race of one of the ball bearings 3 (both bearingsbeing slidable axially along with rotor 6).

The whole of said rotor 6 and said bearing 3 is slidable axially incasing 1 in such manner that the hydrodynamic forces that are broughtinto play may produce, when the pump is driven, a movement of disc 10baway from the corresponding wall of casing 1. Packing ring 11b isequivalent to the packing ring 11 of Fig. 1.

Finally, Fig. 13 shows a modification of the difiusers,

which are given a circular cross section. There is provided, to adjustthe diffuser minimum section S, an axially movable central core 25actuated, for instance, by means of a rack device 26.

It should be noted that the parts of the pump made as above describedwhich are in contact with the fuel may advantageously be subjected to asurface treatment, for instance a chromizing treatment, to reinforcetheir resistance to corrosion.

The pump above described may be used for injection vehicle), theinjection of fuel corresponding in this case either to the maincombustion or to after-burning.

On the other hand, a pump of this kind might be applied to the conveyingof many liquids other than fuels for injection engines, for instance toconvey liquid in a liquid rocket or for conveying liquid (in particularacids) in chemical industry plants.

In a general manner, while I have, in the above description, disclosedwhat I deem to be practical and efiicient embodiments of my invention,it should be well understood that I do not wish to be limited thereto asthere might be changes made in the arrangement, disposition and form ofthe parts Without departing from the principle of the present inventionas comprehended within the scope of the accompanying claims.

What I claim is:

l. A centrifugal pump which comprises, in combination, a casing havingan axial intake at one end thereof and a peripheral discharge, at leastsubstantially radial blades in said casing carried by said rotor on theside thereof turned toward said intake, whereby liquid in said casing isimpelled centrifugally by said blades toward said discharge, a bearingcarried by said casing in line with said rotor at the end of said casingopposed to said intake, a shaft journalled in said bearing operativelyconnected with said rotor for driving it, an annular packing ringcarried by said casing coaxial with said shaft, a disc coaxial with saidshaft slidable axially in said casing, operatively connected with saidrotor for rotation together therewith, said disc being adapted tocooperate at rest with said packing ring to prevent leakage of liquidfrom the inside of said casing through said bearing, a part fixed in theaxial direction with respect to said casing, a part fixed in the axialdirection with respect to said disc, spring means interposed betweensaid two last mentioned parts for urging said disc toward said packingring, packing means mounted on said disc to prevent liquid from leakingalong its hub portion, inclined surfaces carried by the face of saiddisc turned toward said bearing, the inclination of said surfaces beingsuch as to produce, when said disc is driven in rotation, a' reaction ofthe liquid present between said disc and said casing which urges saiddisc axially away from said packing ring, and centrifugal blades carriedby the last mentioned face of said disc and at least as close to theshaft axis as said inclined surfaces to produce a counterpressureopposing a centripetal flow of liquid between said disc and the face ofsaid casing which supports said annular packing rmg.

2. A centrifugal pump which comprises, in combination, a casing havingan axial intake at one end thereof and a peripheral discharge, a rotorin said casing, at least substantially radial blades in said casingcarried by said rotor on the side thereof turned toward said intake,whereby liquid in said casing is impelled centrifugally by said bladestoward said discharge, a bearing carried by said casing in line withsaid rotor at the end of said casing opposed to said intake, a shaftjournalled in said bearing rigid with said rotor for driving it, anannular packing ring carried by said casing coaxial with said shaft, adisc coaxial with said shaft slidable axially on said rotor andoperatively connected therewith for rotation together therewith, saiddisc being adapted to cooperate at rest with said packing ring toprevent leakage of liquid from the inside of said casing through saidbearing, spring means interposed between said rotor and said disc forurging said disc toward said packing ring, packing means mounted on saiddisc to prevent liquid from leaking along its hub portion, inclinedsurfaces carried by the face of said disc turned toward said hearing,the inclination of said surfaces being such as to produce, when saiddisc is driven in rotation, a reaction of the liquid present betweensaid disc and said casing which urges said disc axially away from saidpacking ring, and centrifugal blades carried by the last mentioned faceof said disc and at least as close 'to' the shaft axis as said inclinedsurfaces to produce a counterpressure opposing a centripetal flow ofliquid between said disc and the face of said casing which supports saidannular packing ring.

3. A pump according to claim 2 in which the spring (means for uring saiddisc toward said packing ring consists of a diaphragm which alsoconstitutes the packing means mounted on said disc to prevent liquidfrom leaking along its hub portion.

4. A centrifugal pump which comprises, in combination, a casing havingan axial intake at one end thereof and a peripheral discharge, a rotorin said casing, at least substantially radial blades in said casingcarried by said rotor on the side thereof turned toward said intake,whereby liquid in said casing is impelled centrifugally by said bladestoward said discharge, a bearing carried by said casing in line withsaid rotor at the end of said casing opposed to said intake, a shaftjournalled in said bearing operatively connected with said rotor fordriving it, an annular packing ring carried by said casing coaxial withsaid shaft, a disc coaxial with said shaft slidable axially in saidcasing operatively connected with said rotor for rotation togethertherewith, said disc being adapted to cooperate at rest with saidpacking ring to prevent leakage of liquid from the inside of said casingthrough said bearing, a part fixed in the axial direction with respectto said casing, a part fixed in the axial direct with respect to saiddisc, spring means interposed between said two last mentioned parts forurging said disc toward said packing ring, packing means mounted on saiddisc to prevent liquid from leakingalong its hub portion, inclinedsurfaces carried by the face of said disc turned toward said bearing inthe peripheral portion of said face, the inclination of said surfacesbeing such as to produce, when said disc is driven in rotation, areaction of the liquid present between said disc and said casing whichurges said disc axially away from said packing ring, and centrifugalblades carried by the last mentioned face of said disc, nearer to theaxis of said disc than said inclined surfaces, to produce acounterpressure opposing a centripetal flow of liquid between said discand the face of said casing which supports said annular packing ring. 7

5. A centrifugal pump according to claim 4 in which the periphery ofsaid disc is curved toward the wall of said casing which it faces,whereby the edge of said disc periphery is very close to said casingwall.

6. A pump according to claim 1 in which said disc is provided withorifices for the flow of liquid therethrough.

7. A pump according to claim 2 in which the inside of said casing formstwo circular chambers, to wit a main chamber containing the bladedportion of said rotor and an auxiliary chamber containing said disc,with a throttled passage between said two chambers.

8. A centrifugal pump which comprises, in combination, a casing havingan axial intake at one end and a peripheral discharge, a bearing carriedby said casing at the other end thereof, at least substantially in linewith said intake, a shaft journalled in said bearing, an annular packingring carried by said casing coaxial with said shaft, a disc mounted onsaid shaft coaxially therewith, means for connecting said disc with saidshaft to cause said disc to rotate together with said shaft, said discbeing slidable in said casing in the direction of the shaft axis, saiddisc being adapted to cooperate at rest with said packing ring toprevent leakage of liquid from the inside of said casing toward saidbearing, a part fixed in the axial direction with respect to saidcasing, a part fixed in the axial direction with respect to said disc,spring means interposed between said two last mentioned parts for urgingsaid disc toward said packing ring, at least substantially radial bladeswithin the casing connected to said disc for rotation therewith, wherebyliquid in said casing is impelled centrifugally by said blades urgessaid disc axially away from said packing ring, and

centrifugal blades carried by the same face of said disc and at least asclose to the shaft axis as said inclined surfaces to produce acounterpressure opposing a centripetal flow of liquid between said discand the face of said casing which supports said annular packing ring.

9. A centrifugal pump which comprises, in combination, a casing havingan axial intake at one end and a peripheral discharge, a bearing carriedby said casing at the other end thereof, in line with said intake, ashaft journalled in said bearing, an annular packing ring carried bysaid casing coaxial with said shaft, a disc mounted on said shaftcoaxially therewith, means for 1 connecting said disc with said shaft tocause said disc to rotate together with said shaft, said disc beingslidable in said casing in the direction of the. shaft axis, said discbeing adapted to cooperate at rest with said packing ring to preventleakage of liquid from the inside of said casing through said bearing, apart fixed in the axial direction with respect to said casing, a partfixed in the axial direction with respect to said disc, spring meansinterposed between said two last mentioned parts for urging said disctoward said packing ring, a rotor having at least substantially radialblades thereon within the casing, said rotor being rigidly connected tosaid disc for rotation therewith, whereby liquid in said casing isimpelled centrifugally by said blades toward said discharge, said dischaving inclined surfaces on the face thereof directed toward saidbearing, the inclination of said surfaces being such as to produce, whensaid disc is driven in rotation, a reaction of the liquid presentbetween said disc and said casing which urges said disc axially awayfrom said packing ring, and centrifugal blades carried by the same faceof said disc and at least as close to the shaft axis as said inclinedsurfaces to produce a counterpressure opposing a centripetal flow ofliquid between said disc and the face of said casing which supports saidannular packing ring.

10. A centrifugal pump according to claim 9, in which said dischargeincludes at least one pump diffuser carried by said casing and extendingsubstantially tangent to the surface described by said first mentionedblades, said blades being provided with notches of a shape adapted toaccommodate the inlet of said diffuser.

11. A centrifugal pump according to claim 9, in which said dischargeincludes at least two delivery diffusers carried by said casing andhaving their inlets arranged so that when one diffuser inlet is oppositeone blade 8 edge, the other diffuser inlet is located between twoblades.

12. A centrifugal pump accordingto claim 9, in which said dischargeincludes delivery diffusers carried by said casing and extending to theinside thereof, with means for adjusting the minimum section of saiddiffusers.

13. A centrifugal pump which comprises, in combination, a casing havingan axial intake at one end and a peripheral discharge, a part rigid withsaid casing forming a cylindrical housing at the other end thereof, atleast substantially in line with said intake, a ball bearing mounted insaid housing coaxially therewith, the outer race of said ball bearingbeing slidable axially in said housing, a shaft journalled in saidbearing, a rotor having at least substantially radial blades thereonwithin the casing, said rotor being rigid with said shaft and coaxialtherewith, whereby liquid in said casing is impelled centrifugally bysaid blades toward said discharge, an annular packing ring carried bysaid casing coaxial with said shaft, a disc rigid with said rotor andcoaxial therewith, said disc being adapted to cooperate at rest withsaid packing ring to prevent leakage of liquid from the inside of saidcasing toward said housing, a spring washer interposed between saidcasing and said ball bearing outer race for urging said disc toward saidpacking ring, said disc having inclined surfaces on the face thereofdirected toward said bearing, the inclination of said surfaces beingsuch as to produce, when said disc is driven in rotation, a reaction ofthe liquid present between said disc and said casing which urges saiddisc axially away. from said packing ring, and centrifugal bladescarried by the same face of said disc and at least as close to the shaftaxis as said inclined surfaces to produce a counterpressure opposing acentripetal flow of liquid between said disc and the face of said casingwhich supports said annular packing ring.

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